Fix the case that might let position text cannot get the position.

[andy840119]

Fix the case that might let position text cannot get the position:

• has no main text.
• text in the position text is null or empty.
• start and end index is out of range.
• end index is larger than start index.
• text with ...

How to fix that:

• Move GetFixedPositionText into PositionTextFormatter.
• GetFixedPositionTexts should only fix the duplicated value and move it inside applyPositionTextToBuilder.

Where to add the test:

• maybe TestSceneLyricSpriteTextCharacterPosition -> rename is required

[andy840119]

Found while implementing #203

[andy840119]

Also, TestSceneLyricSpriteTextCharacterPosition should be more focus on the showing the sizing of every char.
.
Should create another test case for checking if text or position has been generate.